# CVE-2026-23904: Apache Kyuubi SSRF in Engine UI proxy

Source: https://junglewise.ai/threats/cve-2026-23904-apache-kyuubi-ssrf-in-engine-ui-proxy  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-29. Updated: 2026-07-29  
License: CC BY 4.0 with a link back

CVE-2026-23904 · Severity: info · Published 2026-07-29

Apache Kyuubi is a distributed multi-tenant gateway for data processing engines like Spark and Flink. A security flaw in its Engine UI proxy allows remote users to force the Kyuubi server to send web requests to any internal or external computer. This could allow an attacker to scan private networks, bypass firewalls, or access sensitive internal services that are not normally exposed to the internet.

Technologies: [Apache Software Foundation Kyuubi](https://junglewise.ai/threats/technologies/kyuubi). Vendors: [Apache Software Foundation](https://junglewise.ai/threats/vendors/apache-software-foundation).

## Quick answers

**Is CVE-2026-23904 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-23904 being exploited in the wild.

**How severe is CVE-2026-23904?** Informational severity, published 29 July 2026.

**Which products and versions are affected?** Apache Software Foundation Kyuubi 1.8.0 to 1.11.x (before 1.12.0).

**Is there a fix for CVE-2026-23904?** A patch was published on 2026-05-29: Pull request to restrict proxy targets submitted Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-23904 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-23904?** Check whether you run Apache Software Foundation Kyuubi at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The Kyuubi Engine UI proxy component improperly validates the host and port parameters provided in the request path. A remote attacker with network access to the Kyuubi REST frontend can exploit this to perform Server-Side Request Forgery (SSRF) or use the server as an open proxy to reach arbitrary network destinations. This can lead to internal network scanning or unauthorized access to internal metadata services. The vulnerability is addressed in version 1.12.0 by disabling the proxy by default and introducing a whitelist configuration ('kyuubi.frontend.rest.engine.ui.proxy.hosts') to restrict allowed destinations.

## Affected products

- Apache Software Foundation Kyuubi 1.8.0 to 1.11.x (before 1.12.0)

## Timeline

- 2026-05-29: patched: Pull request to restrict proxy targets submitted
- 2026-07-29: disclosed: CVE published by Apache Software Foundation

## References

- [https://repo.maven.apache.org/maven2](https://repo.maven.apache.org/maven2)
- [https://github.com/apache/kyuubi/pull/7483](https://github.com/apache/kyuubi/pull/7483)
- [https://lists.apache.org/thread/ps79fcfx49ox9kwgztc5t5bw0tyhck9m](https://lists.apache.org/thread/ps79fcfx49ox9kwgztc5t5bw0tyhck9m)

## Related threats

- [Apache Kyuubi path traversal via Spark config alias bypass](https://junglewise.ai/threats/cve-2026-62391-apache-kyuubi-path-traversal-via-spark-config-alias-bypass)
- [Apache Kyuubi path traversal in REST batch multipart upload](https://junglewise.ai/threats/cve-2026-52680-apache-kyuubi-path-traversal-in-rest-batch-multipart-upload)